


CleanSINg

by Shinobiinu



Category: Undertale (Video Game)
Genre: AU fest, Alternate Universe - Underfell (Undertale), Alternate Universe - Underlust (Undertale), Alternate Universe - Underswap (Undertale), F/M, Hurt/Comfort, Multi, One Shot Collection, Smut
Language: English
Status: In-Progress
Published: 2020-03-06
Updated: 2020-03-11
Packaged: 2021-02-28 21:34:02
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,928
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23044078
Author URL: https://archiveofourown.org/users/Shinobiinu/pseuds/Shinobiinu
Summary: Sometimes to get clean, you have to wade through all the dirty ;D(Basically a collection of Undertale blurbs ranging from fluff to smut. I also thought it would be a good way to figure out personalities for my other fics. Adding tags as I go.)Please send scenario suggestions! I'm up for just about any AU, though I haven't read all of them. Not afraid to research.
Relationships: Papyrus (Undertale)/Reader, Sans (Undertale)/Reader
Kudos: 47





	1. Bump n' Grind

**Summary for the Chapter:**

> Underfell Sans is having a bad day until a cloaked figure helps him relieve some stress.
> 
> Sans POV. Pet play. Assumed consent (both parties consented but Sans just assumes). Public Display.

Grumbling under his breath, Sans waited in line with far too many monsters for his liking. Normally he'd take advantage of his well-honed ability to shortcut to wherever he needed, teleporting his lazy ass wherever it needed to go.

Unfortunately for him, Boss had gotten hold of a brand new collar for him via Alphys. Not just any collar, oh no. It had attack hampering and location tracking abilities embedded. In his glee, the great and maleficent Papyrus had immediately set to testing it out on his favorite subject of dominion.

So what was the delicate skeleton with 1 HP doing standing in a crowd of pissed off monsters? It seems his shortcuts were considered something like an attack and he had been summoned by King Asgore for some inane reason. Without the use of the shortcuts, this elevator was the only route to the big guy…

With a shout, it became apparent the elevator was open and the hoard of violent monsters fought to get inside. Luckily Sans was a pro at slipping into undesired locations (heh) so it was child's play to secure his spot in the back.

The space filled to crowding, the sharp-toothed skeleton glad he had been able to claim his spot. Leaning against the wall as the transport shuddered and swayed as it took off, he heard the sound of pissy voices near the middle of the crowd.

The mass shifted, several voices joining the din.

Sans growled under his breath, the tension making him nervous. If things got too out of hand, there would be nowhere to go and he knew he couldn't take a hit… This was bad. Fuck he couldn't wait for his brother to dispel the damn inhibitor.

As the yelling started in earnest, the smarter monsters crowded the walls in an attempt at avoiding the fight occurring in the center. A plush cloaked figure was firmly pushed against the round skeletons frame. Grunting, he pushed back, but physical strength wasn't his claim to fame. The distinct feel of a feminine shape was pressed into him more, to both his discomfort and growing pleasure.

The masochist in him loved it, the survivor hated feeling so trapped. Still, the ride would be a while…

Giving in, he let his red dripping tongue flop out of his mouth, running it over his pointed teeth as he drooled. Trying to remain subtle, he merely bumped his growing erection against the softly rounded backside before him. To his shock and delight, the lovely rear arched against him.

Barely holding back a groan, he ran his hands over where assumed their waist was, getting and pulling at the soft cloak covered flesh. They began to tremble. He smirked in response and ran a hand down the expansive butt and leg, trailing down to find the edge of the cloak.

As he found his goal, the butt ground against his now solid magic with purpose, soft whimpers barely audible in the ruckus of the elevator despite his proximity. A deep chuckle reverberated through his bones as he molded himself against this dirty, assumedly willing partner.

Running his hand back up along the clothed leg in search of the next hem, he hoarsely growled, “Fuck pet, do you always greet a new friend like this?” They let out a soft moan as he yanked the edge of their pants down, revealing the softest pussy he'd laid eyes on, strange skin though. “Dripping wet for me already? Nnn, pet. This is just what your Master needed.”

His dick was outside his pants faster than it had any right to be, glowing red. Glancing around, he was relieved to see no one had noticed them yet and the flashing lights of the monster's fight in the elevator kept his magic's glow from drawing attention. 

He found a delicately small hand around his other wrist, drawing it towards her heaving chest. Her voice both husky and quietly moaned, “Master… please.”

“You have me thinking you like it out in public like this, huh pet? Well, I bet you'll really love it when I make you scream for me.” Her trembling became more pronounced as he spoke. “Or is it that you like my voice? Heh, if you tell me, I'll be real nice pet.”

He teased her now-sopping entrance with just the tip of his penis, slowly tracing across her folds.

A small squeak erupted as he did so, her hips trying to push back. “I-i… I like both.” She breathed deeply. “But your voice is seriously the sexiest fucking thing I've ever heard.”

At that admission, Sans felt his control snap. He had been meaning to toy with her but… “Fffuck… you’re a fucking good freak pet.” He growled as he thrust deep, shocking a loud gasp from his partner. Her body clutched at his intrusion, tighter than he had in the longest time.

Hissing out a long, “yessss" his hips started rotating to loosen her up enough that he could move, tugging roughly on her nipple as she bit back her vocalizations. Jerking his length out of her as far back as the wall allowed, he slammed in fully sheathing in the process. They both groaned happily.

His breath hitches as he can feel her clenching around his formidable girth, pulling him as deep as possible. Throwing caution to the wind he hammers into the tight wetness without mercy, his jaws sinking into the neck/shoulder juncture despite the cloth in the way.

Lifting her hips, he lifted her center of gravity until the only thing keeping her ‘standing’ was his cock. The wet slap of bone on flesh barely muffled by the almost resolved fight nearby.

“M-master… uhn, yes… we're too loud… And the trip can't be… Ohhh fuck.” She's done well to stifle her sounds thus far, but she was right. The elevator was slowing down. He wasn't going to have a later with her, Boss would make sure of that. This had to be finished now. 

Letting one of her legs down, he reached into his ribcage and began stroking his soul as the pulsing magic cock vibrated. Her response was swift and intense, vaginal muscles milking him for all he was worth, the combination with his own touches was too much and he happily filled the screaming woman to the brim with his crimson liquid.

Everyone swayed as the elevator stopped. Quickly he pulled out, readjusting his clothes as his companion did the same, and without even acknowledging each other, they parted ways.

Later

Waiting… again. Sans’ done quite a bit of that today. The bright light shining past the red-tinted cathedral windows of the judgment hall irritated him as per usual. Asgore said they were waiting for an ambassador from a different country to arrive, and as judge it was his duty to ensure the person wasn't going to be a problem. How in the heck had they even gotten down to the underground to start with, and without alerting himself or his brother? Oh goody, of all the times to have his attacks blocked…

He heard their steps long before he saw them, confident taps across the marble blocks. Closing his eyes he let out a deep breath and looked at them only to freeze in shock.

“H-hello again Master.”


	2. Whispered Somethings

**Summary for the Chapter:**

> God I'm dumb.
> 
> Underlust Sans + Reader, but 3rd person. Voice-kink maybe? I'm not sure.
> 
> Why did I even write this >x<

“Uh, exactly how did you get into my room?” The soft rumble of suspicion leaked into an otherwise sensually deep voice. “I know I'm irresistible, but usually people only get this far if I invite them… And I'm pretty sure we haven't met.”

A soft giggle curled through the room from the human sitting on the bed, his bed. Bright purple hearts for eyes are staring at her form, barely restraining the discomfort of her sudden and unexpected appearance.

“Mm, Sans- dearest… you may not know me but…”

The male - a skeleton monster dressed in a sleeveless purple hoodie, edges trimmed in cyan faux fur; a short black shirt with a cyan heart graphic in the center barely going down to the bottom of his ribs; shiny long black pants barely hugging his pelvis trail into mid-calf purple boots - found himself staring at the ceiling as his body hit the dirty carpet, breath knocked out of him from the sudden impact. No sooner had his mind regained control that he found the face that had previously startled him pressed close to his own, the pressure of their body on top of his own making movement impossible. Letting out a low growl to the stranger, he began summoning his magic only to be interrupted with the tip of a velvety tongue pressed into his mouth. Due to his world, his very nature, he instinctively kissed back, his own smooth purple tongue wrestling for dominance.

The kiss lasted for a couple minutes before Sans regained his focus, pulling back he took a few deep breaths.

“Don't worry, I'm not here to do anything dangerous. I just got a little too excited to meet you. I've heard a lot about you from a mutual friend.” Tenderly, her fingers brushed over his chest bone through his shirt. “I even came up with a technique I'd like to try with you, if you don't mind.”

He can't help but laugh as his body relaxes under her touch, despite himself. “you force yourself on me and then have the audacity to ask my consent? hah, wow.” He teases as he considers his options but ultimately... “alright, I suppose I can indulge you.”

She smiles brightly, fingers trailing lower. “Thank you, I'll even do all the work. So just relax.”

Given the day he previously had, he was more than willing to let someone else do all the work. Shrugging momentarily, he lay back. The soft-touch caressing his bones slowly moved lower towards the sensitive lower ribs, a small groan escaping. She really was being very careful… maybe too careful. “heh. you know, i’m not gonna break. go ahead and live a little.”

That smirk worried him, but the careful way she ran her fingers over every inch of bone continued. “Oh, I know what I’m trying to do here, just be patient. I promise, if it all works out as I plan, you’ll be fulfilled in more ways than one.” That kind of statement earned a raised eye ridge, but if that’s how she was going to play it, he may as well relax.

“don’t you at least want to take my shirt off? the shirt’s dulling your progress hun.”

“Actually, it’s better if you keep it on. It would be too tempting to stray from my ‘technique’ if I could see all of those sexy bones.”

“alright, but if i get too comfortable, i may just take a nap instead. can we at least take this to the bed?”

She nods, and Sans finds himself being quickly picked up and plopped on his own rumpled sheets, a laugh escaping as the woman quickly reclaims her place atop him. She was obviously worried he was going to escape. Silly human. Still, now that he had the comfort of his bed against his tired bones, the restarted caresses really were close to lulling him to sleep.

“‘m liking the massage, but this isn’t gonna get you anywhere… (yawn) sexually at least.”

A small pout played over those luscious lips. “Hold on, I’m getting there, just gotta lay the groundwork.” He couldn’t help but chuckle.

“Hey Sans?”

“yes sweetheart?”

“Do your customers ever ask for anything other than the rough and dirty?”

Rough and dirty? He chuckles, “not really hun, why?”

“It seems that it would be rather tiring, getting treated that way all the time.”

The skeleton contemplated for a moment, and while he was happy to go along with whatever his partners were after, it was true that things seemed to form a rather narrow pattern after a while. He wasn’t necessarily tired of anything, but something new would be rather nice. Heck, he’d been planning to pay one of his alternate selves a visit tomorrow, just as a way to spice things up. He replied with a mere shrug.

The touches began trailing down the side of his spine, and while it was enjoyable there wasn’t anything remotely sexual about the way he was being touched. It was just simply relaxing. Well, whatever.

“Sans, I’m gonna start now.” The hints of nervousness were foreign to the way she’d spoken earlier. Color Sans surprised. “So please, listen with an open heart and… don’t say anything.”

He pantomimed pulling a zipper across his mouth and smiled encouragingly. For all the girl’s previous bravado, she was certainly showing a large amount of innocent vulnerability. It was adorable, but he couldn’t help but wonder about the whys, or at least until she pressed close against him and opened up those sweet lips of hers. Her whispering voice made his soul pulse lowly under his ribs.

“You are an amazing person, and as much as you like to deny it, your laziness is because you can’t help but want to push others into the spotlight. You tire yourself taking care of everyone around you, so the few times you have to yourself are usually spent worrying about the few things you can’t control. Sans, you are loved by so many people, not just your brother, and it’s because you always make those little gestures that show you care. Not a big showing, just small things. Little hints of understanding that add up over time.”

Sans was caught off guard, the tender words uttered so honestly as she stroked her fingers across his skull were stirring something deep within, the beating of his soul sped up and couldn’t help but stare into those shimmering eyes filled with adoration.

“You are worthy of happiness. You store so many problems deep inside you but somehow you keep it locked away where no one can see and… you deserve to let that go. Please let that go, you take on so much for so many other people. I would like to protect you, comfort you, to help you relax and forget about your trouble, whatever it is. You are appreciated.”

The pressure of her fingertips gliding over his skull felt like she was literally pulling out all the stress, tension and day to day fears from his mind and soul, letting them wash away with the steady stream of sweet compliments she was raining down. A sense of wonder played over his mind as lavender tears welled at the corners of his sockets. What in the world was she doing to him? It was only compliments, but he suddenly felt so renewed and loved… it was overwhelming. Hell, even his body was responding.

“You are a living, breathing sexual fantasy. Smart and sexy.”

As her words turned towards the sensual, his soul responded in kind. Pleasure at the simple feeling of appreciation, the gentle and demure touches previously lavished on his bones were tingling at the memory, the feeling becoming a rising warmth.

“Do you realize how beautiful you are?”

Her hands stopped petting his skull, instead pulling his hands up towards those soft lips, pressing tender kisses along his phalanges. One hand began softly stroking along the bones of his arm, adding to the now surging sensations pulsing in his senses.

“Pleasuring you is an honor. Your mind, your body, deserve to be worshipped.”

His breath left him in deep panting sighs as she pressed kisses into his palms, his whole body was supercharged with sensitivity. Those sparkling eyes remained lovingly staring into his own heart-shaped lights. His breath hitched as he saw something shift within her, realizing he was staring directly into her soul. He was being drawn in.

“The thought of sleeping with you is the only thing keeping me sane. You are the very definition of irresistible.”

He felt deep in his own soul move, not physically - just emotionally. Still, the depth of connection between himself and the woman on top of him was almost tangible, thick in the air. Her words stroked his soul in a way that hands never could, the very feel and intent of her need for him to climax drove him insane. His body pulsed. He was close.

Amazed that mere words could drive him to the brink; he hadn’t even conjured genitalia, but he was so close to cumming, he couldn’t focus on anything but her. The way she breathed against his face, chests pressed together so he could feel the rise and fall of her lungs. The way her weight settled against his stimulated bones, firm and comfortable. The soft wisps of her hair swept across his skull where their foreheads met. Their mouths so close to one another, yet not touching - as if interrupting her sweet words would end him. His body shook, the sensations rivaling that of his best orgasm, but he waited. He waited for her words to bring him to that place; it had been a long time since someone saw to his needs without it being a transaction. Care for the sake of being cared for. 

“I didn’t even know I could want someone this badly. The moment I saw you, I knew I wouldn’t be able to keep my hands off you, but you deserve better than that so I tried, but I couldn’t hold back.“

Shaking, he could read in her eyes that she wanted him to wait, and oh god it was so hard not to succumb to those beautiful thoughts she put to voice. He barely held himself back, training barely holding despite all his experience. She was right, he did deserve to be appreciated, to not have his problems weighing him down, to experience all the things he ensured his loved ones would have. He would start with this. He would wait for it, but oh stars he wanted to come so badly. The pressure of his gathered magic pressing on his soul. It was edging on painful, but he held.

With the brush of her lips against his cheek, she whispered, “Please cum for me Sans.” And he was in bliss, his mind awash with the sweetness of her love and care. His body jerked as the purple magic rushed forth, ejaculating from every crevice, the feeling of all the pressure body and mind had built up over the years forcing a small sob to escape his lips even as they were spread in the happiest smile he’d worn in ages.

Despite now being covered in his purple jizz, she continued to press tender little kisses to his jawline as his euphoria subsided.

“I know you’re still really tender right now, but could you please check your soul? I, uh, could leave if you need your privacy.”

His whole body was like an overly sensitive nerve-ending (which is hilarious since he didn’t have any) but he shook his head, shifting so he could pull his soaked shirt away from his ribcage. He was about to laugh at her odd sense of privacy when he stilled, staring at his soul - to be more specific, his stats.

Somehow, he had gained hp from all of this. 10/10 it said. His bafflement made him look back at the female, brightly smiling at him, then back down to double-check.

“W-what… how in the…?”


	3. Picking up the Pieces p.1

**Summary for the Chapter:**

> This is one story I've been working on for a bit and I was intending it to be a one-shot, but I think it's kinda running long, so I'm gonna split it into 2 chapters. Consider this the intro!
> 
> ... it's gonna get sad, just a warning. Next chapter that is.
> 
> Underswap Papyrus, Sans, and Reader. Relationship chaos. No smut this chapter.

Papyrus POV (kinda?)  
\------

A lovely giggle chimed through the air as the hollow thud of a sturdy glass honey jar was dumped carelessly on the bartop. “Huehue, goodness me dearie, I haven't seen you hit the honey this hard in a good long while. What is the occasion?”

The spider-monster set yet another jar on the counter beside the plethora of others before her surly customer. He merely grunted in agitation, leaning his elbows against the counter as he played with the jar lid absentmindedly.

Taking his time, he finally tipped his head back with the jar to his malleable bone jaws trapping the thick golden liquid. Small globs dropped onto his favorite orange hoodie joining the many old honey stains. Lowly burning pinpoints of light stared at the bartending spider as she kept herself pleasantly busy wiping down the bar.

“you remember when I might've mentioned that my bro was taking some class for his new job? he was so excited that he had met lots of humans who wanted to save people like he did and it was hilarious cause there was one friend he was so nervous to impress even though my bro is so great so really he has no reason to worry ‘cause,“ His tirade was halted by a sudden hiccup. “gave me so many chances to tease him… stars, I wish I had put a stop to it then.”

Raising an eyebrow as he rambled, the woman smiled. “Sounds like sweet little Sans got himself a crush. Oh dearie, this will be fine. That brother of yours has a good head on his shoulders.” She couldn't help but titter a bit on how overprotective her favorite regular was about his smaller brother. The skeletons had always been a bit oddly close in her opinion but to each their own.

Of course, that seemed to be exactly what the tall male did not want to hear. Making a face of disgust he set the half drank honey down. “No, Muffet it's not that simple. He's only known the human for like a month and he's already talking soul-bonds and kids. And you know he doesn't joke around about that shit.”

Well, that was rather surprising. The smaller brother was very genuine and as far as she knew he was a total innocent… perhaps she would have to rethink that assumption.

“hey muffet?”

“Yes Papyrus?”

“can i stay with you? … the human’s over for the night.”

It wasn't like they hadn't spent time together after hours, but it was rare for the lanky jokester to come out and ask. This human must really be something to drive Papyrus out of the house, especially when Muffet could read that it was taking everything he had not to drive them away from his precious sibling. It wasn't often she said no to him, so she didn't.

\---

Papyrus returned the next day to find his younger brother beaming as he held the human’s hand tightly. Refusing to think about what that meant, he sullenly watched tv, doing his best to ignore the blatant affection radiating from the pair. 

“Brother! Y/n and I have finally made our engagement official, and I was wondering when you think your next free day off would be. I have already set everything up so…”

Papyrus’ mind was reeling _engagement!?_ They hadn’t even started officially dating or anything yet… right? Was he really hearing this right?

I t ‘ s o n l y b e e n a m o n t h . . .

Papyrus was a man that hated confrontation. Even now the thought that had he stepped in sooner he would have had more time to fix things a better way was only making things worse. Knowing his excitable brother wouldn’t read subtext if he tried to talk him down any other way than a direct confrontation set the tired skeleton’s posture into a tense hunch.

“seriously bro? i think you’re rushing into things. you barely know each other!”

The look of hurt in those soft blue eye lights sent a guilty pang into Papyrus’ soul, but it was for his own good. “you can’t just assume because they’re nice to your face that they’re not plotting something. it’s usually the quiet ones you have to watch out for the most.” Turning his face in anger at the human for causing such a problem, he glared fiercely as they flinched.

“Papyrus! I- what? Chara is a human, and we love them! How can you say all humans are evil plotting bad guys? It’s not like you to be so incredibly close-minded.” The barely held cyan tears slowly trickled down the softer skeleton’s face as Sans found his shaking voice. Carefully clutching at the human’s hand, he positioned her behind his body as if expecting his brother to attack.

“You know what? It’s fine if you don’t approve, we’re together and that’s all that matters.”

As the two small figures left the house, Papyrus had a horrible sinking feeling. In all things, Sans had always been on his side. Why was this human that _he had only barely met_ more important? Had he just lost his brother? The floor slanted and he found himself sitting on the floor. He’d really messed up this time, hadn’t he? With a small self-depreciative chuckle, he sprawled out onto the floor. He wasn’t wrong, humans were dirty, filthy, lying manipulators, but he couldn’t lose his only family to them. He couldn’t bear to think of a life without his brother’s infectious energy or encouraging smiles to bolster his normally low mood. Breathing slowed, tears flowed, and he vaguely realized everything was going black. Ah well. This is only what I deserve was the last thought before he blacked out.

\------  
Human POV  
\------

Holding tightly to Sans’ hand as he tearfully dragged you away from his house, you slowly dragged your heels, hampering your progress just enough to get the upset skeleton to turn and look at you, wiping his face as the luminescent tears continued to trickle down.

“Are you alright my dear? That certainly didn’t go how I expected.”

Shaking your head, you wrapped your arms around the shaking skeleton. “There’s got to be another way we can talk him into...”

“He wouldn’t listen.” Sans gently intercedes, pulling you close even as he glanced around the surroundings, eyeing anything for danger. “Once Papy sets his mind on a subject there isn’t much anyone can do about it. Maybe, if we had more time I could…” Letting out a forlorn sigh, the soft digits curled gently around your face so he could look into your eyes before nuzzling his teeth ridge across your forehead in a pseudo-kiss. “The magnificent Sans will work with his brother to reach a better understanding in time. For now, we should get settled while we work out a plan. I don’t want you stressing out about anything that you don’t need to.”

Lovingly, you snuggled close as you wiped his tears away. You allowed him to steer you towards the next goal, unknown to you but you had full trust in your new bond-mate.

Unknown to the poor beanpole skeleton, the CPR class wasn’t the first time Sans and you had met.

One lovely day in early spring, a thunderstorm decided that despite the brilliant sunshine and lack of clouds, it would find a way to water all those thirsty flowers, and so the heavens dumped forth all the water. You had been at the park looking at all the cute animals at an adoption event, contemplating if you could convince your roommate to help you sneak one in. The sudden chaos of the downpour coupled with the thunder strikes left many reeling, handlers scrambling to attend soggy, terrified animals. Turning to see if you could help, you realized you heard a soft sobbing from a nearby bush. 

Parting the soaking leaves, you found yourself staring into the panic-blown empty eye sockets of a skeleton monster. Asking if he was okay, it soon became apparent that he was in no condition to reply, so you did the only thing you could think of as another crash resounded from the sky, his shaking picking up pace at the same moment. Taking out your headphones, you pulled up your music and pulled the cowering monster up much more easily than you had expected seeing that he was only a few inches shorter than you. Settling the headphones on his confused head, you pushed play and gently guided him towards the nearest covered location, a bus stop.

In the aftermath, you hadn’t said much but his gratitude was boundless, just like everything else about him, especially after the water shorted out your headphones. He insisted on keeping in contact, to make sure he could repay you of course. His sweetness had won you over instantly and while you never were the kind of person to believe in love at first sight, you certainly could admit attraction definitely works that fast.

It turns out that he liked most of the songs on your playlist so your topic of conversation started just naturally stemming from there, but spread out to all aspects of life as he became a regular fixture, mostly through text, though somehow you’d always find you and he would end up constantly running into each other.

The day you both showed up to class was just another of those days and with a laugh, you both worked together like you had been doing this your whole life and that’s when you came to realize your true feelings for him.

You felt a bit guilty knowing how much Sans loves his brother. He’s at least half of what he talks about on any given subject and that family love is one of the things that you absolutely adore about him. You had really hoped to make a good impression on Papyrus when you came over to meet him and for a sleepover, but it seems your (then unknown) mutual attraction was too much for the lazy guy to handle because not even 30 minutes into your visit he disappeared and never returned. Which, if you’re honest, might’ve changed everything.


End file.
